ssize_t readahead(int, off_t, size_t);
int sync_file_range(int, off_t, off_t, unsigned);
ssize_t vmsplice(int, const struct iovec *, size_t, unsigned);
ssize_t readahead(int, off_t, size_t);
int sync_file_range(int, off_t, off_t, unsigned);
ssize_t vmsplice(int, const struct iovec *, size_t, unsigned);